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2025 Vol. 45, No. 11 Published: 2025-11-01

	3001	Advances in the Application of Machine Learning to the Spectrum Detection of Gases
		ZHANG Ying^{1, 2}, ZHANG Chi^{1, 2}, SHI Jian-bo^{1, 2}, LIU Si-si^3*
		DOI: 10.3964/j.issn.1000-0593(2025)11-3001-10
		Artificial intelligence (AI) technology has garnered significant attention in spectral detection recently, establishing a data-driven scientific research paradigm. Machine learning (ML) exhibits advantages in exploring correlations within high-dimensional and complex spectral data. It enhances detection efficiency and accuracy, thereby effectively addressing challenges in the spectral detection of gas mixtures. This paper introduces the fundamental principles of ML, common algorithms, and the general workflow for modeling of spectral data. It briefly reviews various spectroscopy-based gas detection techniques with typical applications, and provides an up-to-date overview (since 2020) of ML advancements in mixed-gas spectral detection. ML-driven spectroscopy technologies for gas show great potential across diverse fields, including industrial process control, early cancer diagnosis, environmental monitoring, and earth observation systems. Specifically, this work explores ML applications in qualitative identification and quantitative analysis of gas mixtures, as well as hyperspectral imaging. Finally, the paper discusses critical challenges and prospects for the practical implementation of ML-based gas spectral detection technologies. This review aims to provide novel insights and recommendations for researchers in gas spectroscopy detection and sensing, thereby advancing and expanding ML applications in this field.
		2025 Vol. 45 (11): 3001-3010 [Abstract] ( 7 ) PDF (7441 KB) ( 5 )

	3011	Design and Research of an Integrated Imaging Method of Snapshot Computed Spectral Polarization on UAV
		LIU Yi, ZHANG Xue-min, YU Yue, ZHAO Hai-bo, LIU Yan-li, REN Wei-he, ZHENG Guo-xian
		DOI: 10.3964/j.issn.1000-0593(2025)11-3011-09
		Target detection and recognition technology play an important role in the field of remote sensing. Spectral polarization imaging technology not only obtains the two-dimensional image information of the target, but also obtains the spectral information and polarization information of the target, which can distinguish “different objects with the same spectrum,” highlight the target, “identify the authenticity”, and improve the detection and recognition probability of the target in the complex background environment. The current polarization spectroscopy imaging system has many drawbacks, such as a complex structure, a large volume and weight, and an inability to image in real time. To solve these problems, an integrated imaging method based on snapshot calculation of spectral polarization is proposed. The main optical path is shared between the polarization channel and the spectral channel, and the beam splitter prism is used to divide the polarization channel and the spectral channel. The polarization channel is directly imaging, and the spectral channel is composed of the coding plate, Amici prism, and collimation system. By utilizing the telecentric optical path to enhance the imaging quality of the system, the optical system and spectral elements were designed and optimized to achieve real-time synchronous acquisition of spectral and polarization information. Based on the above technical route, the principal prototype is integrated, and the prototype is tested in the laboratory darkroom. The final indicators are: working band: 400~900 nm, imaging resolution: 0.1 m, field of view: 29.09°, spectral resolution: 10 nm, prototype weight: 2.75 kg. The real-time imaging test was carried out outdoors, and the polarization state images and spectral curves of different ground objects were obtained. The imaging effect was good, meeting the expected target. This method compensates for the shortcomings of traditional methods and provides a new and effective technical means for obtaining multidimensional information in snapshot polarization spectra.
		2025 Vol. 45 (11): 3011-3019 [Abstract] ( 10 ) PDF (32374 KB) ( 3 )

	3020	Research Progress of Structural Characterization of Coal by FTIR, XRD and Raman Spectroscopies
		TIE Wei-bo¹, WANG Pei¹, ZHU Zhe-xuan¹, WANG Qi^1*, HUANG Jun-chen¹, LI Xian-chun²
		DOI: 10.3964/j.issn.1000-0593(2025)11-3020-07
		To deeply understand the nature of coal, make efficient and reasonable use of coal resources, and respond to the national dual-carbon policy and sustainable development strategy, in-depth research on the molecular structure of coal is an effective way. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), and Raman spectroscopy offer the advantages of non-destructive analysis, rapidity, accuracy, simplicity, and both qualitative and quantitative analysis for coal structure detection. The three spectral techniques can effectively obtain different structural information about coal macromolecules, including the microcrystalline structure characteristics of carbon, the amorphous carbon structure characteristics, and the characteristics of various functional groups. The quantification and characterization of coal structure characteristics provide basic theoretical guidance for rational selection, use, and analysis of the behavior characteristics of the coal coking process. At the same time, the study of coal structure plays a positive role in the promotion and application of spectral technology in the coking industry. This paper reviews the application and progress of three spectral detection technologies in coal structure characterization, systematically summarizes the development of the three spectral technologies, as well as the specific methods and principles of the coal structure research process, including the attribution of characteristic peaks, the separation method of characteristic peaks, and the calculation methods of different structural characteristic parameters of coal. Research progress on the structure evolution of coal and the coking process, including the relationship between structure, composition, and performance, and the correlation between structure evolution and coke forming behavior. Combined with the development of science and technology and the existing research results, the bottleneck problems faced by three kinds of spectral technology in the process of coal structure research and improvement directions are put forward: to develop more scientific and reliable spectral analysis methods and theories, and establish a good correlation between coal structure and its properties; The spectrum technology is linked with other equipment to provide more comprehensive structural information; Intelligent and integrated spectrum detection equipment to achieve industrial online detection and intelligent data analysis; The establishment of a spectral analysis database, the realization of data collection and sharing, for the in-depth exploration of coal structure and enhance its practicability to provide a powerful condition.
		2025 Vol. 45 (11): 3020-3026 [Abstract] ( 8 ) PDF (2498 KB) ( 2 )

	3027	Study on Spectroscopy and Associated Mineral Characteristics of Turquoise From Shizigou, Xichuan, Henan
		DUN Jin-han¹, YANG Ming-xing^{1, 2*}, LIU Ling¹, JIANG Yan¹, YUAN Ye^{1, 3}, WANG Yi¹
		DOI: 10.3964/j.issn.1000-0593(2025)11-3027-08
		Shizigou of Xichuan County, Nanyang City, Henan Province, is located in the eastern extension of the turquoise mining area in the eastern part of the Qinling Mountains, and is one of the important turquoise mining areas in the central mining belt of Hubei, Henan, and Shaanxi. However, compared with turquoise in Hubei and Shaanxi, the research on turquoise in Henan is still insufficient. In this paper, infrared spectroscopy, Raman spectroscopy and LA-ICP-MS were used to analyze the spectroscopic and geochemical characteristics of Shizigou turquoise, focusing on the rare earth elements and trace elements of Shizigou turquoise, and the mineral assemblage and structure of turquoise were studied by X-ray powder crystal diffraction and scanning electron microscopy. The results show that Shizigou turquoise is composed of thin plates, short columnars, and fine flake crystallites. The distribution characteristics of rare earth elements are the relative loss of light rare earths and the relative enrichment of heavy rare earths, and have the geochemical characteristics of high Fe, Cu, Ba, U, V, Zn content, and low Ca content. Typical impurity minerals include quartz, graphite, bonattite, apatite, dickite and hematite, etc., and the surrounding rock mineral assemblage is mainly quartz, accompanied by barite, lepidocrocite, and a small amount of clay minerals such as kaolinite, chlorite and illite, which have important indicative significance for the low-temperature hydrothermal metasomatism and weathering leaching composite metallogenic environment of Shizigou turquoise, which provides a scientific basis for improving the domestic turquoise research and exploring the source of raw materials for early turquoise handicrafts in China.
		2025 Vol. 45 (11): 3027-3034 [Abstract] ( 8 ) PDF (33225 KB) ( 9 )

	3035	Field Comparison Analysis of Spectroradiometer and Electrothermic Solar Radiometer
		LIU Li-ying^{1, 2, 3, 4}, LI Ning³, ZHENG Feng^{1, 2, 3, 4}, HU Xiao-xu³, LI Hui³, SHAO Chang-liang⁵, CHONG Wei⁵, WU Zhi-feng⁶, HUA Wei-dong^{3, 4}, ZHANG Yong-hong^{1, 2}
		DOI: 10.3964/j.issn.1000-0593(2025)11-3035-13
		The precise measurement of solar spectral irradiance is crucial in fields such as meteorological monitoring, climate change research, and solar energy applications. Traditional thermopile radiometers have been widely used for long-term observations, but their measurement accuracy is limited due to spectral mismatch errors. Spectroradiometers, as advanced precision measurement instruments, can provide high spectral resolution data, offering a new technical approach for refined measurements of solar radiation. This study systematically analyzes the measurement consistency and sources of deviation between spectroradiometers and thermopile radiometers through field intercomparison experiments. The results indicate that under clear-sky conditions, the measurement data from both instruments exhibit a high linear correlation(DNI fitting residuals <0.5%, GHI fitting residuals <5%). In the solar spectral absorption peak regions, the spectroradiometer reveals more detailed spectral structures, making it useful for evaluating the spectral errors of thermopile radiometers. Based on the ISO 9060: 2018, this study verifies the feasibility of using spectroradiometers to quantify the spectral errors of thermopile radiometers. It highlights the significant influence of the solar zenith angle on measurement errors. Under high optical air mass conditions (AM>5), the measurement results from spectroradiometers and thermopile radiometers exhibit more pronounced nonlinear deviations, reflecting the interplay among atmospheric scattering characteristics, instrument field-of-view angles, and spectral response curves. The findings from the field intercomparison analysis suggest that spectroradiometers serve as a valuable supplementary tool for refined solar radiation measurements and are essential for characterizing the spectral errors of thermopile radiometers. In the future, the integrated application of spectroradiometers and traditional radiometers could further enhance the accuracy of solar radiation observations, providing more reliable data support for meteorology, environmental monitoring, and renewable energy applications.
		2025 Vol. 45 (11): 3035-3047 [Abstract] ( 15 ) PDF (33134 KB) ( 9 )

	3048	Research on a Genetic Algorithm-Optimized XGBoost Algorithm for Quantitative Analysis of Coal Quality Using Laser-Induced Breakdown Spectroscopy
		ZHU Ting-ting¹, PAN Cong-yuan^{1, 2, 3*}, ZHAO Qian-jin¹, XUE Hua-qin^{2, 3}, SHEN Yuan^{2, 3}, ZHANG Bing^{2, 3}
		DOI: 10.3964/j.issn.1000-0593(2025)11-3048-09
		To address the high-precision demand for online coal quality detection in coal-fired copper smelters, this study proposes a genetic algorithm (GA)-optimized extreme gradient boosting decision tree (XGBoost) ensemble model (GA-XGBoost), enhancing the industrial applicability of laser-induced breakdown spectroscopy (LIBS) for complex coal analysis. To overcome overfitting and limited generalization in traditional XGBoost caused by hyperparameter sensitivity, GA-XGBoost implements a GA-based global search strategy to adaptively optimize key hyperparameters (e. g., learning rate, tree depth, regularization parameters) coupled with binary-encoded chromosome representation for dynamic spectral feature selection, effectively suppressing noise in 14 328-dimensional LIBS data. Validation employed 59 standard coal samples from Datong, Shanxi (bituminous coal) and Ordos, Inner Mongolia (lignite). Preprocessing via adaptive iteratively reweighted penalized least squares (airPLS) and Savitzky-Golay filtering reduced spectral dimensions to 500, with dominant features identified by SHapley Additive exPlanations (SHAP) values. Comparative experiments demonstrated GA-XGBoost's superiority over XGBoost, random forest (RF), support vector machine (SVM), multiple linear regression (MLR), and partial least squares (PLS) in predicting ash content and calorific value. For ash content, GA-XGBoost achieved a 0.053 increase in R², 0.964% reduction in RMSE, 0.324% decrease in MAE, and 1.494-percentage-point lower RSD. For calorific value, it yielded a 0.003 R² improvement, 0.021 MJ·kg^-1 RMSE reduction, 0.07 MJ·kg^-1 MAE decrease, and 0.871-percentage-point RSD reduction. External validation using 20 unmodeled on-site coal datasets confirmed robustness in industrial environments, with errors constrained within 1% (ash) and 0.5 MJ·kg^-1 (calorific value). The GA-LIBS integration addresses spectral interference and generalization challenges, establishing a unified framework for real-time multi-parameter coal analysis. Field deployment in an operational copper smelter demonstrated seamless integration into LIBS online systems, providing a technically viable pathway toward clean and efficient coal utilization.
		2025 Vol. 45 (11): 3048-3056 [Abstract] ( 8 ) PDF (7389 KB) ( 3 )

	3057	Spectral Separability Analysis and Band Selection for Heavy Metal Inversion in Water Using Correlation Coefficient Heatmaps
		LIANG Ye-heng¹, LAO Xiao-min², DENG Ru-ru^{1, 3*}, NI Hua-hong¹, ZHAO Tong-tong¹, HUANG An-feng⁴, GUO Zhi-peng⁵, LI Yu-hua⁶, ZHANG Rui-wu¹
		DOI: 10.3964/j.issn.1000-0593(2025)11-3057-09
		The concept of “green economy”, which balances rapid urban economic development with environmental protection, has become a societal consensus. Integrating emerging remote sensing technologies (e. g., satellites and drones) with traditional methods can establish a multidimensional monitoring system, enabling a more efficient balance between economic and environmental goals. A critical challenge for expanding remote sensing applications lies in overcoming technical bottlenecks related to parameters that cannot be extracted via remote sensing. Monitoring heavy metals in water, a valuable yet unresolved area of environmental remote sensing, encounters the issue of spectral separability in multi-parameter inversion through satellite remote sensing. To address this, the reflectance spectra of four compounds (copper sulfate, potassium ferricyanide, potassium ferrocyanide, and ferric chloride) were measured using a spectrometer within the wavelength range of 350~1 050 nm. Key findings include: Copper sulfate exhibits a reflectance peak at 441 nm; Ferric chloride shows a “wave-like” gradual increase until 906 nm, followed by a decline; Potassium ferricyanide peaks at 767 nm; Potassium ferrocyanide peaks at 826 nm, with the latter having a trough at 988 nm. The reflectance spectra of these four compounds intersect at two places: copper sulfate and potassium ferrocyanide intersect at a wavelength of 492 nm, while copper sulfate, ferric chloride, and potassium ferricyanide intersect in the wavelength range of 576~584 nm (centered at 580 nm). Consequently, the Ratio Copper Index (RCI) was proposed to differentiate copper sulfate from the three iron compounds. Two remote sensing models were employed to analyze the mathematical principles behind spectral separability. Utilizing a linear spectral unmixing model, pairwise correlation coefficients among ten heavy metal compounds (copper sulfate, potassium ferricyanide, potassium ferrocyanide, ferric chloride, cadmium oxide, lead tetroxide, lead chromate, cadmium sulfide, lead sulfate, and lead sulfide) were calculated across varying spectral resolutions and visualized through heatmaps. The results showed that there are many valuable phenomena, laws, and references about the separability between these ten heavy metal compounds. Ultimately, a dynamic band selection strategy for remote sensing inversion was proposed, which adjusts the number of compounds and bands in accordance with correlation heatmap results. The research results provide a deep discussion of the mathematical nature of spectral separability between compounds and the solution of remote sensing models, further deepening the algorithmic theoretical basis for solving remote sensing models. This research promotes the implementation of heavy metal concentration inversion in water at the satellite image level in the future.
		2025 Vol. 45 (11): 3057-3065 [Abstract] ( 90 ) PDF (7759 KB) ( 21 )

	3066	*Quality Grading of A. mongholicus* Based on Effective Component Content and Hyperspectral**
		WU Qiang¹, ZHAO Peng², WANG Meng², ZHAO Cai-quan², BAI Li-ge², GUO Jia-hua², GAO Xue-feng², HOU Ding-yi³, GENG Zhi-gang⁴, LU Ling^2, LIU Jie^2
		DOI: 10.3964/j.issn.1000-0593(2025)11-3066-06
		Huang qi is the dried root of the legume Astragalus membranaceus (Fisch. ) Bge. var. Mongholicus (Bge. ) Hsiao (A. mongholicus) or Astragalus membranaceus (Fisch. ) Bge., which has the functions of bu qi gubiao. However, its traditional quality evaluation methods are time-consuming, destructive, and subjective. The purpose of this study is to establish a rapid and non-destructive quality classification model of A. mongholicus by using ground feature hyperspectral technology and the key effective component content. Two hundred A. mongholicus root samples were collected from Guyang County, Baotou City, Inner Mongolia Autonomous Region; Astragaloside (AS) and calycosin-7-glucoside (C7G) content was determined by HPLC. Based on the effective component content, the samples were divided into four quality grades: ultra high AS, high AS, high C7G and ordinary by K-means clustering analysis; The diffuse reflectance spectrum data of each sample powder in the range of 350～2 500 nm were obtained using ASD FieldSpec 4 surface spectrometer, and SG smoothing pretreatment was performed; The competitive adaptive reweighted sampling (CARS) algorithm was used to select the characteristic wavelength from the full band spectrum, and the partial least squares discriminant analysis (PLS-DA), support vector machine (SVM) and random forest (RF) classification models were constructed based on the characteristic wavelength. The results showed that: (1) the average content of AS in ultra high AS (28), high AS (44), high C7G (36) and ordinary (92) were 0.130%, 0.112%, 0.096% and 0.089%, respectively, and the average content of C7G was 0.039%, 0.034%, 0.046% and 0.029%, respectively; (2) The spectral curves of A. membranaceus samples with different quality grades were significantly different in shape and absorption intensity, and the effective component content showed a significant correlation with the spectral reflectance in a specific wavelength region. The AS content had the highest correlation with the 1 890～1 900 nm band (r=0.621), while the C7G content had the highest correlation with the 1 356～1 365 nm band (r=0.636); (3) Among the three classification models, RF model performed best, and the overall accuracy of its correction set and validation set reached 94.8% and 92.3%, respectively, and the kappa coefficient reached 0.893. PLS-DA and SVM models also showed good classification performance. This study proved that the ground feature hyperspectral technology combined with CARS feature selection and RF classification model can realize the rapid and non-destructive grading of A. mongholicus quality, which can provide a new way for the evaluation of Huang qi quality.
		2025 Vol. 45 (11): 3066-3071 [Abstract] ( 5 ) PDF (1735 KB) ( 8 )

	3072	Investigation of a Typical Dust Pollution Process in Jiuquan Based on an Aerosol Lidar and Multi-Source Data
		WANG Sui-chan¹, SUN Lin-hua², GAO Peng¹, JI Cheng-li³, ZHANG Shuai^4*
		DOI: 10.3964/j.issn.1000-0593(2025)11-3072-09
		To investigate the pollution characteristics, transmission pathways, and potential source regions of sandstorm weather in Jiuquan City, this study utilized monitoring data from ground-based air quality stations, meteorological stations, and atmospheric aerosol lidar, as well as ERA5 reanalysis datasets. The present study employed a combination of the backward trajectory HYSPLIT model and the potential source contribution factor (PSCF) analysis method to investigate a typical sandstorm event that occurred in May 2024. The findings indicate that coarse particulate matter had a substantial impact on the dust storm, with an average PM_2.5/PM₁₀ ratio of 0.24. The impact of the duststorm in question can be divided into three distinct stages, as evidenced by the observations made at ground-based air stations. These stages are as follows: the pre-pollution stage, the significant impact stage (during which there was a duststorm impact), and the pollution dissipation stage. During the period of significant impact, the mean concentrations of PM_2.5 and PM₁₀ at ground-based air stations were 415.3 and 3 425.9 μg·m^-3, respectively, with the duststorm persisting for a duration of 13 hours. The vertical observation results of atmospheric aerosol lidar showed that the dust cloud was primarily distributed below 3 km in altitude, exhibiting a distinct low-altitude transport characteristic. The extinction coefficient and depolarization ratio of the dust exhibited an initial increase, subsequently followed by a decrease, during the process of dust transport and dissipation. During the period of significant impact, the extinction coefficient of the dust cloud ranged from 1.0 to 4.6 km^-1, and the depolarization ratio ranged from 0.30 to 0.36. The findings of the meteorological investigation suggest that this sandstorm was predominantly triggered by the synergistic impact of a low-pressure trough in the upper atmosphere and low-level wind fields, with the prevailing easterly winds acting as the primary agent responsible for the rapid transportation of sand and dust to Jiuquan City. Research conducted on the transport pathways and potential source regions indicates that the sand and dust predominantly originated from the east (accounting for 66.13%) and northwest (accounting for 24.19%) directions. Potential source regions include the Badain Jaran Desert and the Kumtag Desert, among others, with the Badain Jaran Desert contributing the most significantly to dust transmission to Jiuquan City. The present study provides a scientific basis for the prevention, control, and early warning of dust pollution in Jiuquan City.
		2025 Vol. 45 (11): 3072-3080 [Abstract] ( 12 ) PDF (33884 KB) ( 8 )

	3081	Highly Sensitive Detection Method for Trace Paclobutrazol Residues Based on Terahertz Metamaterial Resonant Enhancement Combined With ECO-SVR
		MAO Xiao-dong, HUANG Zhi-kai, LIU Yan-de, HU Jun^*
		DOI: 10.3964/j.issn.1000-0593(2025)11-3081-09
		As a widely used growth regulator, paclobutrazol plays a significant role in ensuring crop yields and improving the quality of agricultural products. However, suppose it is overused and leaves excessive residues. In that case, it will not only pollute the environment but also adhere to the surface of agricultural products, posing a potential threat to consumer health. Therefore, it is urgent to establish an efficient, sensitive, and non-destructive method for the precise detection of paclobutrazol content in agricultural products. In view of the problems of complex pretreatment, long time consumption, and insufficient sensitivity in traditional detection techniques, this paper proposes a non-destructive and highly sensitive detection method for trace paclobutrazol pesticide residues by combining terahertz metamaterial sensors with intelligent optimization modeling algorithms. In this study, an “L”-shaped composite double-peak structure terahertz metamaterial sensor was designed and fabricated. 21 samples of paclobutrazol solutions with different concentrations were prepared. After adding drops, drying, and cooling, the transmission spectra of each concentration in the range of 0.7～3.5 THz were collected, and their spectral characteristics were analyzed. The spectral data were processed by combining pretreatment algorithms such as 1^st D, 2^nd D, SNV, and MSC, with feature selection algorithms, including CARS, UVE, IRIV, VIP, VISSA. The educational competitive optimization algorithm (ECO) was introduced to optimize the hyperparameters of the support vector regression (SVR) model, thereby constructing the optimal regression model. The results show that the “L”-shaped structure metamaterial sensor proposed in this study has good resonance enhancement ability; In the range of 0.7～3.5 THz, as the concentration of paclobutrazol increases, the terahertz transmission spectrum shows a significant decrease in amplitude and redshift of the resonance peak, showing a good concentration response relationship; The ECO-SVR model has better model effects in the full band than other optimization methods; The 2^nd D-VISSA-ECO-SVR model shows the best prediction accuracy and fitting ability, with the model's R_P, RMSEP and MAE being 0.974 9, 0.069 0 and 0.054 4; The LOD of the model was calculated to be 0.215 μg·mL^-1 by fitting the real concentration and predicted concentration of paclobutrazol. This paper combines the ECO algorithm with terahertz metamaterial technology. It combines pretreatment and feature extraction techniques to achieve high-sensitivity and non-destructive detection of paclobutrazol residues, verifying the effectiveness and superiority of the ECO optimization algorithm in the field of spectral detection, and providing an efficient and practical technical path for pesticide residue analysis.
		2025 Vol. 45 (11): 3081-3089 [Abstract] ( 9 ) PDF (18933 KB) ( 1 )

	3090	Research on Non-Destructive Prediction Method of Tomato Quality Indicators Using Hyperspectral Imaging and Extreme Learning Machine
		HUANG Lian-fei¹, WU Sha¹, HUANG Ren-shuai^{1, 2*}
		DOI: 10.3964/j.issn.1000-0593(2025)11-3090-08
		Hyperspectral imaging technology, with its unique advantages of acquiring continuous and abundant spectral information of samples and effectively reflecting internal compositional characteristics, provides a new technical pathway for the rapid and non-destructive detection of key physicochemical indicators of fruits and vegetables. Based on this, this study focuses on tomatoes as the research object, targeting their key physicochemical indicators—including Soluble Solids Content (SSC), lycopene content, and vitamin C content—to explore rapid and non-destructive prediction methods for these indicators. To enhance the accuracy and robustness of the prediction model, the hyperspectral data were first preprocessed using the Standard Normal Variate (SNV) transformation to mitigate the interference of scattering and spectral drift, followed by the selection of effective feature bands based on the Genetic Algorithm (GA). Further, Backpropagation Neural Network (BP) and Extreme Learning Machine (ELM) prediction models were respectively constructed to compare their performance differences in predicting various quality indicators. The results showed that ELM outperformed the BP model in predicting lycopene, SSC, and vitamin C. Compared to the BP model, the correlation Coefficient of the Prediction set (R²_p) for ELM increased by 7.5%, 11.4%, and 9.8%, respectively; the Root Mean Square Error (RMSEP) decreased by 25.0%, 22.2%, and 10.4%, respectively; and the Relative Prediction Deviation (RPD) increased by 20.3%, 25.3%, and 28.0%, respectively. Notably, the RPD values of the ELM model in predicting lycopene, vitamin C, and SSC all exceeded 2.6, reaching a good level of prediction accuracy. This study offers a reliable and efficient technical solution for the rapid and non-destructive detection of key quality indicators in tomatoes. Also, it lays a methodological foundation for the application and promotion of non-destructive quality detection technologies for fruits and vegetables.
		2025 Vol. 45 (11): 3090-3097 [Abstract] ( 7 ) PDF (4982 KB) ( 4 )

	3098	*Measurement of Flame 2D Temperature Distribution Based on CH^ Emission Spectra**
		WANG Yi-jia^{1, 2}, YANG Chao-bo^{1, 2*}, CAO Zhen^{1, 2}, PENG Jiang-bo^{1, 2}, YU Nan-jia³, HAN Ming-hong^{1, 2}, LI Wei-ran³, ZHANG Xu-teng^{1, 2}, YU Xin^{1, 2}
		DOI: 10.3964/j.issn.1000-0593(2025)11-3098-07
		Temperature is one of the critical parameters in combustion diagnostics, and obtaining flame temperature holds important scientific significance and practical value. Molecular emission spectra thermometry, owing to its non-contact measurement capability, high upper temperature measurement limit, and simple system configuration, is frequently employed for flame temperature measurement in harsh environments characterized by high temperature and pressure. Constrained by the dimensional limitation of the slit in the grating spectrometer, most of the recent research on this technique has been confined to zero-dimensional (0D) and one-dimensional (1D) measurements, making it difficult to achieve the goal of obtaining a two-dimensional (2D) temperature field of flame through a single measurement. Therefore, this paper incorporated a 2D-to-1D conversion module into the traditional emission spectra temperature measurement system and investigated 2D emission spectra thermometry. Firstly, the emission spectral fitting thermometry algorithm was established based on the principle of molecular emission spectra thermometry, and the process of emission spectra thermometry was formulated. The simulated result of the CH^* emission spectrum at a rotational temperature of 2 500 K was compared with the spectrum generated by the molecular emission spectrum simulation software LIFBASE, yielding the coefficient of determination (R²) of 0.96. This verified the feasibility of the emission spectral fitting thermometry algorithm. Secondly, the 2D-to-1D conversion module was designed, a 2D distribution reconstruction algorithm was established, and the process for acquiring the 2D temperature distribution of the flame was developed. Furthermore, a 2D emission spectra measurement system was constructed based on the 2D-to-1D conversion module. Finally, the 2D emission spectra measurement system was employed to conduct 2D measurement of CH^* emission spectra from the local flame within a model rocket engine. The accumulated CH^*emission spectra were subjected to denoising and baseline removal. The temperatures at different spatial positions were derived by fitting simulated spectra to the measured spectra. Subsequently, the 2D distribution reconstruction algorithm was applied to obtain the local flame's 2D temperature field and the corresponding R² profile of spectral fitting. From the measurement result of the 2D temperature distribution of local flame, it can be concluded that the temperature measurement system constructed in this paper is capable of resolving two temperature data points with the spatial interval of 0.50 mm, and the measurement result of 2D temperature distribution is consistent with the flame morphology. In the 2D distribution of spectral fitting R², all R² values are greater than 0.8, and positions with R²>0.9 account for 76.5%, which validates the reliability of the temperature measurement result.
		2025 Vol. 45 (11): 3098-3104 [Abstract] ( 9 ) PDF (6511 KB) ( 1 )

	3105	Polarization Optimization of Quantitative Analysis of K Element in Paddy Field Soil by Laser-Induced Breakdown Spectroscopy
		LIANG Jia-qi^{1, 2}, YAO Ming-yin^{1, 2}, LIU Mu-hua^{1, 2}, LUO Zi-ling², WEI Hai-bo², XU Jiang^{1, 2*}
		DOI: 10.3964/j.issn.1000-0593(2025)11-3105-08
		This study demonstrates enhanced precision and stability in laser-induced breakdown spectroscopy (LIBS) for determining potassium (K) content in paddy soil via polarization-resolved optimization. A polarization-resolved spectroscopic system was built to collect LIBS and polarization-resolved LIBS (PRLIBS) data of paddy soil samples under varying laser excitation energies. A comparative analysis of full spectra highlighted the advantages of PRLIBS. Within 744～775 nm, 3D spectral intensity maps of LIBS and PRLIBS were generated, with the K I 766.49 nm line (most intense characteristic peak) selected for analysis. Both techniques showed consistent spectral trends with increasing excitation energy, validating polarization-resolved optimization for LIBS. Linear correlation analysis between K signal intensity and excitation energy for samples N2K1—N2K4 revealed higher R² values for PRLIBS (0.995 86, 0.979 51, 0.996 11, 0.993 57) than LIBS (0.970 16, 0.944 98, 0.991 53, 0.989 24). PRLIBS, via Glan-Thompson prism birefringence, filters high-polarization ordinary light (o-ray) and transmits low-polarization extraordinary (e-ray), reducing background noise interference on plasma characteristic peaks and improving K detection stability in paddy soil. Comparison of signal intensity distributions and relative standard deviations (RSD) showed superior PRLIBS stability at 35, 55, and 75 mJ, indicating strong characteristic line resolution by the polarizing prism under low excitation energy. Calibration curve fitting at 35 and 55 mJ yielded higher R² for PRLIBS (0.944 82, 0.958 32) than LIBS (0.150 69, 0.473 95), confirming enhanced characteristic signal stability. A PRLIBS quantitative model was established, with the 55 mJ excitation prediction model showing lower root mean square error (RMSE) than 35 mJ. PRLIBS significantly improves spectral stability and accuracy, particularly under low excitation energy, providing a valuable reference for rapid paddy soil nutrient detection.
		2025 Vol. 45 (11): 3105-3112 [Abstract] ( 11 ) PDF (11045 KB) ( 4 )

	3113	Solvent Effect on the Excited State Intramolecular Proton Transfer Process of 2,2′-bipyridine-6,6′-dicarboxylic Acid
		Gulimire Yaermaimaiti^{1, 2}, SONG Xin-tian¹, AN Huan¹, Bumaliya Abulimiti^1, XIANG Mei^1
		DOI: 10.3964/j.issn.1000-0593(2025)11-3113-09
		In this study, we used time-dependent density functional theory (TD-DFT) to calculate 2,2′-bipyridine-6 at the Cam-b3lyp / 6-31G (d, p) theoretical level. The bond length, bond angle, infrared (IR) vibration spectrum, highest occupied molecular orbital (HOMO), and lowest unoccupied molecular orbital (LUMO) of 2,2′-bipyridine-6,6′-dicarboxylic acid (BP6DC) in cyclohexane, dichloromethane, and dimethyl sulfoxide solvents were studied. In addition, the hole-electron orbitals of BP6DC in these three different solvent environments were simulated by Multiwfn and VMD software. At the experimental level, we measured its absorption and emission spectra using a steady-state spectrometer. Our results show that in cyclohexane (CYH) solvent, due to the inherent symmetry of the BP6DC molecule, the changes of parameters (bond length, bond angle) related to two hydrogen bonds O12—H18…N10 and O24—H25…N19 are consistent. On the contrary, in dichloromethane (DCM) and dimethyl sulfoxide (DMSO) solvents, the change of bond length and bond angle showed the opposite trend. Through the analysis of the potential energy surface, the effect of solvent polarity on the hydrogen bond in the excited state of the BP6DC molecule was explained. We conclude that BP6DC can undergo excited-state double proton transfer in cyclohexane solution. On the contrary, in DCM and DMSO solutions, the molecular symmetry is destroyed, resulting in only a single proton transfer, and this single proton transfer has dual channel characteristics.
		2025 Vol. 45 (11): 3113-3121 [Abstract] ( 5 ) PDF (12554 KB) ( 3 )

	3122	Development of Predictive Models for Fatty Acids Content in Multiple Pork Muscle Sites Using Spectroscopic Techniques
		ZHANG Sheng-jie¹, ZHAI Chen^2, XING Wei-hai², FENG Xiao-hui², YANG Ying-kang², YANG You-you², SHI Chao³, YANG Zhou², WANG Wen-xiu^1
		DOI: 10.3964/j.issn.1000-0593(2025)11-3122-08
		The fatty acids in pork are not only a concern for consumer health but also significantly impact the sensory quality, processing performance, and market competitiveness of the meat. With the progress in nutritional research and the development of the food industry, the rapid detection of fatty acid content in pork has become a crucial direction for enhancing meat quality and meeting the diverse demands of consumers. This study aimed to develop an on-site rapid detection method for fatty acids in multiple muscle tissues of three-way crossbred pigs, based on spectroscopic technologies. Portable near-infrared (NIR) and Raman spectrometers were used to collect spectral data from 14 muscle parts (e.g., longissimus dorsi, psoas major, and trapezius) of 10 three-way crossbred pigs at slaughterhouses. Simultaneously, gas chromatography was employed for the accurate quantification of 28 fatty acids and fatty acid groups. After preprocessing the spectra with a second derivative and standard normal variate (SNV) transformation, competitive adaptive reweighted sampling (CARS) was applied to select feature wavelengths, followed by the establishment of partial least squares (PLS) quantitative prediction models. The results demonstrated that models based on Raman spectral data outperformed those using NIR spectroscopy. Consequently, Raman spectroscopy was utilized to develop 28 prediction models for key indicators, including total fatty acids (FA), saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), C16:0, C18:0, and C18:1. Among these, 25 models achieved a prediction coefficient of determination (R²) greater than 0.85 and a residual predictive deviation (RPD) exceeding 2.5. Research indicates that establishing a prediction model for fatty acid content in multi-site muscle tissues using Raman spectroscopy is feasible. The development of this method provides technical support for predicting various fatty acid contents in pork at slaughter sites.
		2025 Vol. 45 (11): 3122-3129 [Abstract] ( 7 ) PDF (8084 KB) ( 3 )

	3130	Structural and Technological Analysis of Polychrome Layers in Excavated Artifacts From the Mausoleum of the From Qin Shihuang's Emperor Using Spectral Technologies
		WEI Xin-yi^{1, 2}, WANG Dong^{1, 2*}, LI Xiao-xi³, FU Fei³, LAN De-sheng³, XIA Yin³, ZHOU Ping³
		DOI: 10.3964/j.issn.1000-0593(2025)11-3130-09
		The Emperor Qin Shihuang's Tomb has yielded exceptional archaeological finds, notably the Terracotta Army-celebrated among the “Eight Wonders of the World”. These artifacts offer crucial insights into the craftsmanship of Qin Dynasty lacquerware. This paper focuses on polychrome layer samples from two distinct contexts: (1) Terracotta Army in Pit 1, and (2) chariot wheel fragments recovered from the western burial chamber. Analytical techniques, including FTIR, Raman, XRD, and SEM-EDS, were employed to characterize structures and composites of the polychrome layers. The results indicated that all samples had a multilayered structure consisting of a lacquer ash layer and a pigment layer, with a clear boundary between them. Cinnabar, lead white, and carbon black in the pigment layer were identified, and the lacquer ash layer was composed of raw lacquer and inorganic filler. Notably, there are significant differences in the lacquer ash layers between the Qin Terracotta and chariot wheels. The lacquer ash layer of the former exhibited a fine-grained structure dominated by CaCO₃, suggesting the use of CaO-based lime powder during lacquer formulation. In contrast, the lacquer ash layers of the wooden chariot wheels exhibited two structural compositions: coarse ceramic tile ash primarily containing SiO₂ and Al₂O₃ and a fine-grained CaCO₃-dominated matrix. SEM-EDS mapping revealed distinct stratification patterns in lacquer ash layers of the chariot wheels. For the No.3 sample, A mixture of ash between tile ash and lime powder during the lacquering process was used. But the No.4 sample displays a four-layer structure formed by sequentially applying layers of tile ash lacquer and lime lacquer, resulting in an alternating arrangement of coarse and fine ash layers. Finally, the statistical results of the pigments used in the polychrome layers of the robe figures and armor figures excavated from Pit 1 of the Terracotta Army indicate a preference for bright attire among commoners in the Qin Dynasty. This contrasts sharply with the Qin rulers' preference for black, which was considered prestigious in their ritual system. This study not only clarifies the structure and techniques of the lacquer and painted layers on the terracotta figures and the chariots from the large tombs to the west of the mausoleum but also provides an in-depth analysis of the coloration of the Qin figures' attire, offering crucial scientific evidence for the conservation and research of polychrome artifacts unearthed at The Emperor Qin Shihuang's Tomb.
		2025 Vol. 45 (11): 3130-3138 [Abstract] ( 9 ) PDF (76619 KB) ( 1 )

	3139	FTIR Spectroscopic Characterization of Crude Oil Maturity and Salinity Regulatory Mechanisms
		ZHANG Han-jing¹, WANG Fei¹, WANG Tao¹, LI Jing-song¹, LI Zhen¹, WANG Juan¹, WANG Jin-wei¹, HAO Peng-ling¹, LI Su-mei², TIAN Miao¹, ZHANG Yu¹, LIU Huan¹
		DOI: 10.3964/j.issn.1000-0593(2025)11-3139-06
		To achieve breakthroughs in the rapid evaluation of crude oil maturity, this study innovatively established a maturity discrimination model based on Fourier Transform Infrared Spectroscopy (FTIR). The crude oil from the source rock series of Es₃ and Es₄ in the Dongying sag of the Jiyang depression is used as the research object. By analyzing the maturity parameters of biomarkers such as sterane (C₂₉αββ/(ααα+αββ), C₂₉20S/(20S+20R) ) and terpane (Ts/(Ts+Tm)), the intrinsic correlation between FTIR and thermal evolution degree of crude oil was established. In this study, Origin2025 software was used for baseline correction and Gaussian-Lorentz mixture model (Voigt function) deconvolution technology to analyze the infrared spectral characteristics. The relationship between the characteristic peak area ratio (A∑CH₂/A∑CH₃) of the aliphatic hydrocarbon vibration region (2 800～3 000 cm^-1) and maturity was revealed for the first time. The ratio decreases from 4. 33 in the low maturity stage (C₂₉αββ/(ααα+αββ)=0.30) to 1.03 in the high maturity stage (C₂₉αββ/(ααα+αββ)=0.60). Combined with molecular dynamics analysis, it is found that the β-cleavage of long-chain alkanes is the main mechanism for the decrease of the relative abundance of the —CH₂— group with the increase of maturity. The long-chain alkane structure in the low-mature oil is intact, while the mature oil produces significant short-chain alkane chaining due to thermal cracking. Under the same maturity conditions, the A∑CH₂/A∑CH₃ value of crude oil in a high-salinity environment ( gammacerane/ C₃₀ hopane=0.81) was significantly increased by 23.5% compared with that in a freshwater environment. Molecular simulation shows that salinity can effectively delay the decay process of the —CH₂— group in long-chain alkanes by inhibiting sulfide cracking reaction, which provides new experimental evidence for the influence of paleosalinity on the evolution path of organic matter. Compared to traditional gas chromatography-mass spectrometry (GC-MS) technology, this method achieves three major technological innovations. (1) Nondestructive testing characteristics. Only a small amount of sample (<50 μL) is required to complete the analysis, avoiding sample loss caused by complex pretreatment. (2) The analysis efficiency jumped, and the single-sample detection time was compressed to 5 minutes. (3) The breakthrough of in-situ applicability can be directly applied to in-situ maturity evaluation of unconventional reservoirs such as shale oil and tight oil, and successfully overcomes the dependence of conventional methods on movable hydrocarbon content. The research results provide a molecular-scale tool for evaluating unconventional resources, such as shale oil, which has both theoretical and engineering application value.
		2025 Vol. 45 (11): 3139-3144 [Abstract] ( 9 ) PDF (4726 KB) ( 1 )

	3145	Comparison Study of Four Transfer Learning Architectures for Degree of Polymerization Assessment of Insulating Paper Across Different Instruments
		LI Han, SUN Wei-zhe, CHEN Xi-yuan, ZHANG Guan-jun, LI Yuan^*
		DOI: 10.3964/j.issn.1000-0593(2025)11-3145-08
		Near-infrared spectroscopy (NIRS) has become an important nondestructive technique for assessing the degree of polymerization (DP) of insulating paper as an alternative to traditional chemical methods. As a typical data-driven chemometric approach, NIRS often suffers from amplitude shifts in spectral data collected across different instruments, which severely limit its generalizability and large-scale deployment in engineering applications. In this work, we construct a model transfer scenario involving four representative spectrometers to analyze inter-instrument spectral discrepancies. We systematically compare the transfer learning fine-tuning performance of four mainstream deep neural network architectures under different parameter configurations, investigate the effect of layer-freezing strategies on transfer performance, and identify the optimal network structure and hyperparameter combination within a predefined search space. The results show that significant spectral amplitude differences exist among instruments, leading to drastic degradation of predictive performance when a source-domain model is directly applied to the target domain, rendering the model nearly ineffective. Freezing strategies improve fine-tuning performance by stabilizing the network; specifically, freezing the front-end feature extraction layers while fine-tuning the higher-level decision layers enhances transferability without compromising stability. Among the four tested architectures—MLP, 1D-CNN, EOT, and ResNet—EOT achieved the lowest error in the source domain but performed worse after fine-tuning in the target domain, whereas ResNet exhibited higher source-domain error than EOT but achieved better fine-tuning performance. This indicates that source-domain training error is not strongly correlated with transfer effectiveness. Overall, a three-branch ResNet network incorporating multi-scale Inception modules achieved the best target-domain performance, with an RMSE of 78.5 and a MAPE of 8.6% after fine-tuning, significantly outperforming the other models. These findings provide theoretical support for constructing NIRS modeling frameworks with cross-instrument generalizability.
		2025 Vol. 45 (11): 3145-3152 [Abstract] ( 5 ) PDF (20628 KB) ( 2 )

	3153	Study on Spectral On-Site Rapid Identification Method of Cable Insulation Material Models
		SUN Wei-zhe, LI Han, CHEN Xi-yuan, ZHANG Guan-jun, LI Yuan^*
		DOI: 10.3964/j.issn.1000-0593(2025)11-3153-07
		Fast and accurate identification of insulation material types can prevent the mixing and misuse of raw materials, which is a key part of quality control in cable production. The traditional method using Fourier Transform Infrared Spectroscopy (FTIR) for sampling inspection has several drawbacks, including high cost, low efficiency, and poor adaptability to field conditions. It is difficult to meet the need for fast and full inspection of raw materials. This paper proposes a method for fast identification of cable insulation material types by combining near-infrared spectroscopy with a one-dimensional convolutional neural network (1D-CNN). Six common cable insulation materials were used as the research objects. Their spectral data were collected using a near-infrared spectrometer, and a 1D-CNN model with two convolution-pooling units was built. The model leverages its ability to extract local features from high-dimensional near-infrared spectral data, thereby identifying spectral differences between various material types. Based on this, various spectral preprocessing methods were applied to remove unwanted interference. The modeling performance under each strategy was compared systematically, and the second derivative of the spectrum using Savitzky-Golay smoothing was found to be the best preprocessing method. Bayesian optimization was introduced to adjust key model parameters and improve recognition accuracy automatically. The optimized model achieved an identification accuracy of 95.00%, a weighted average precision of 95.07%, a weighted average recall of 95.00%, and a weighted average F1 score of 0.950 4, which are significantly better than traditional machine learning models. The results show that combining the 1D-CNN model with near-infrared spectroscopy enables fast, accurate, and non-destructive identification of cable insulation material types, with strong potential for field application. This study provides a reliable solution for the rapid screening and testing of cable insulation materials on a large scale, offering strong technical support for building an intelligent quality control system throughout the entire insulation material process.
		2025 Vol. 45 (11): 3153-3159 [Abstract] ( 8 ) PDF (14423 KB) ( 4 )

	3160	UV-Visible Spectral Characteristics and Quantitative Analysis of the MnSO₄-H₂SO₄ System
		XU Yan-li, XU Fu-yuan, DUAN Ning^*
		DOI: 10.3964/j.issn.1000-0593(2025)11-3160-09
		The complex pretreatment requirements and delayed analytical response inherent in conventional methods constitute major challenges for monitoring high-acid, high-manganese systems (H₂SO₄≤2 mol·L^-1, Mn²⁺≤1.2 mol·L^-1) within the hydrometallurgical industry. For effective process management and optimization, rapid and accurate monitoring of Mn²⁺ concentration within high-concentration H₂SO₄ matrices is crucial. This study aimed to develop a rapid and direct determination method based on ultraviolet-visible (UV-Vis) spectroscopy to overcome spectral interference arising from the significant overlap between the absorbances of Mn²⁺ and H₂SO₄. The goal was to enable direct quantification of Mn²⁺ within MnSO₄-H₂SO₄ systems, thereby providing an innovative solution for high-frequency industrial monitoring. The study systematically characterized the spectral properties of H₂SO₄ solutions across a concentration range of 0～18 mol·L^-1. Utilizing spectral similarity analysis techniques—including Spectral Correlation Measure (SCM), Euclidean Distance Measure (EDM), and Spectral Information Divergence(SID)—wavelengths exhibiting minimal H₂SO₄ interference were identified. Furthermore, the detection sensitivity for Mn²⁺ was enhanced using a long optical path strategy (100 mm). A robust quantitative model was established for Mn²⁺ within the industrially relevant concentration range (≤60 g·L^-1). Key findings demonstrate that the absorption peak of H₂SO₄ within the 180～230 nm region (λ_max≈185～195 nm) shows substantial overlap with the MnSO₄ absorption. The core sources of interference identified were the concentration-dependent wavelength shift of this H₂SO₄ peak and the enhanced SO^2-₄ absorption due to Mn²⁺ coordination. Crucially, H₂SO₄ exhibits negligible absorption at 400 nm, a wavelength where the Mn²⁺ complex showed stability. Model validation yielded excellent performance: predicted absolute relative errors \|RE\| and relative standard deviations (RSD) both remained below 5%, with a coefficient of determination (R²) exceeding 0.99. This research pioneered a collaborative spectral interference decoupling-long optical path enhancement strategy. A UV-Vis spectroscopic detection method was developed that achieves rapid and accurate quantification of Mn²⁺ in high-concentration H₂SO₄ solutions, eliminating the need for dilution or pretreatment. This approach offers advantages in speed, cost-effectiveness, and precision, making it well-suited for monitoring requirements in industrial leaching and electrolytic refining processes. The strategy holds significant guiding potential for analyzing other inorganic salt electrolysis systems and provides a crucial foundation for improving hydrometallurgical efficiency while reducing environmental burdens.
		2025 Vol. 45 (11): 3160-3168 [Abstract] ( 6 ) PDF (8247 KB) ( 1 )

	3169	Research on Rapid Quantitative Analysis Method of Total Reflection X-Ray Fluorescence Spectroscopy Without Internal Standard Addition
		LIU Xiao, CHU Bin-bin, FAN Xing-tao, ZHAN Xiu-chun^*
		DOI: 10.3964/j.issn.1000-0593(2025)11-3169-05
		Total reflection X-ray fluorescence spectroscopy (TXRF) technology usually uses internal standard method for quantitative analysis. It is not always easy to select an internal standard element in practical applications. Additionally, the sample preparation process can be cumbersome, which is not conducive to field analysis. Therefore, this article proposes a rapid TXRF quantitative analysis method that eliminates the need for internal standard addition by utilizing Ar, which is constantly present in the air, as the internal standard element for quantitative calculation.A rapid TXRF quantitative analysis method for Cr, Mn, Ni, Cu, Zn, Sr, and other elements in groundwater samples without internal standard addition was established. Blank sample tests were conducted on 24 quartz reflectors, revealing minimal variation in the total and net intensities of Ar, with precision values of 1.05% and 1.09%, respectively. This provides theoretical and operational feasibility for using Ar as an internal standard element. Under the specified measurement conditions, the limits of detection (LODs) of Cr, Mn, Ni, Cu, Zn, and Sr were all less than 2.00 μg·L^-1, and the precision of each element was better than 10%. TXRF measurements of five different concentrations of M22809 standard solutions showed that the TXRF values obtained using Ar as the internal standard and those using Ga as the internal standard were consistent with the certified values, demonstrating the feasibility of using Ar as an internal standard element for TXRF quantitative analysis. Further validation was performed by analyzing three groundwater samples, where the TXRF results using Ar or Ga as the internal standard were in good agreement with ICP-MS measurements, confirming the reliability of using Ar as an internal standard element. On-site TXRF analysis of four groundwater samples in Laizhou, Yantai, TXRF results consistent with ICP-MS measurements, demonstrating the effectiveness of the method for field applications. When using Ar as an internal standard element for TXRF quantitative analysis, to improve the accuracy, it is necessary to first measure the standard solution in parallel three times to determine the Ar concentration value. However, since Ar and Cl are adjacent elements,high Cl content in samples may cause spectral overlap, which can affect the quantitative analysis results. Therefore, when using Ar as an internal standard element for TXRF quantitative analysis, it is generally suitable for samples with relatively simple matrices, such as groundwater, mineral water, and other clean water samples. This method is rapid and reliable, providing technical support for rapid on-site analysis of water samples.
		2025 Vol. 45 (11): 3169-3173 [Abstract] ( 7 ) PDF (1208 KB) ( 3 )

	3174	Probing Acidic OER Mechanisms on Cobalt/Iridium-Based Electrocatalysts via In Situ Surface-Enhanced Raman Spectroscopy
		HU Ce-jun², HU Yan-fang^1, XIE Wei^3
		DOI: 10.3964/j.issn.1000-0593(2025)11-3174-08
		The acidic oxygen evolution reaction (OER) is a core process in proton exchange membrane water electrolyzers. However, the highly corrosive environment and complex reaction pathways pose significant challenges for developing efficient catalysts. Understanding the dynamic evolution of catalytically active sites and the reaction mechanism under realistic operating conditions is crucial for designing highly stable acidic OER catalysts. In this work, highly active and stable CoIrO_x catalysts were prepared via a displacement method. Electrokinetic studies revealed that during catalyst activation, cobalt leaching generates surface vacancies, which in turn expose iridium sites that are oxidized to the active Ir⁵⁺ phase, thereby promoting the reaction. In situ surface-enhanced Raman spectroscopy (SERS) combined with H/D isotope experiments confirmed that OOH is the key intermediate species in the acidic OER process. Furthermore, ¹⁸O isotope labeling was used to probe the dynamic changes in the catalyst's surface microstructure. A pronounced blue shift in the Ir—O vibrational peak at OER potentials indicated that the OER on CoIrO_x follows a lattice oxygen oxidation mechanism (LOM). This work provides new insights into the reaction mechanisms of CoIr-based catalysts and offers a novel approach for exploring OER pathways.
		2025 Vol. 45 (11): 3174-3181 [Abstract] ( 7 ) PDF (13589 KB) ( 2 )

	3182	Research on a Method for Evaluating the Usage Status of Orthodontic Archwires Based on Laser-Induced Breakdown Spectroscopy Technology
		XU Zi-heng^{1, 2}, YANG Guang^{1, 2}, QU Dong-ming^{1, 2}, WANG Yu-zhuo^3*, DING Yu⁴
		DOI: 10.3964/j.issn.1000-0593(2025)11-3182-08
		With the increasing prevalence of orthodontic treatment among the general public, orthodontic archwires—as the core medium for transmitting orthopedic forces and guiding tooth movement during orthodontic procedures—are increasingly becoming a focal point for researchers. The complex oral environment, rich in acids, alkalis, enzymes, and salts, subjects orthodontic wires to chemical corrosion, ion leaching, and microbial adhesion during use. Consequently, issues such as allergic reactions, gingival inflammatory complications, and enamel demineralization caries have emerged as significant challenges in orthodontic treatment that cannot be overlooked. This study developed an on-site rapid analysis method for orthodontic wires based on laser-induced breakdown spectroscopy (LIBS). Samples included copper-nickel-titanium, standard nickel-titanium, and heat-activated nickel-titanium wires used in patients' mouths for 1-6 months. Following preliminary delineation of wire observation zones, the method analyzed trends in key elements (Ca, Ni, Ti) across varying ablation cycles. Results indicate that the first five ablation cycles at a single point capture spectral information of the biofilm formed through plaque-wire interaction, reflecting microbial metabolite accumulation on the wire surface. Beyond five cycles, spectra become consistent, primarily characterising the alloy composition of the wire itself. By analyzing variations in Ca spectral line intensities across different archwire regions, the distribution of dental plaque within the orthodontic patient's oral cavity can be reflected. This facilitates monitoring of archwire usage status, patient oral hygiene levels, and dental health conditions. This method provides an intuitive and reliable basis for early caries prevention during orthodontic treatment, enabling clinicians to intervene in the demineralization process before visible white spots appear on the patient's enamel. Secondly, for existing caries lesions, a retrospective analysis of the correlation between wire calcium distribution patterns and patient cleaning habits helps distinguish whether caries development stems from inadequate cleaning or individual susceptibility. This provides orthodontists with an objective technical means to understand the most authentic and reliable oral hygiene outcomes in orthodontic patients, compensating for the limitations of traditional empirical judgments. The plaque-wire surface calcium differential model established in this study holds promise for providing novel solutions to the high incidence of caries, a significant challenge during orthodontic treatment.
		2025 Vol. 45 (11): 3182-3189 [Abstract] ( 6 ) PDF (12682 KB) ( 4 )

	3190	Photochromism and Its Spectral Characteristics of Pink CVD Synthetic Diamond
		YUE Su-wei^{1, 2}, LI Kun^{1, 2}, GAO Shi-jia^{1, 2}, JIN Li-li^{1, 2}
		DOI: 10.3964/j.issn.1000-0593(2025)11-3190-08
		The formation of NV color centers in colorless synthetic diamonds involves multi-stage processes, including high-temperature, high-temperature high-pressure treatment, irradiation, and low-temperature annealing, resulting in a pink hue. Additionally, a small number of synthetic diamonds produced by the chemical vapor deposition (CVD) method may exhibit a pink color due to the presence of NVH⁰ and SiV^- color centers. Pink synthetic diamonds undergo a photochromic effect when exposed to short-wave ultraviolet radiation at 225 nm. An experimental study was condu cted on pink CVD synthetic diamonds by exposing them to short-wave ultraviolet radiation and diamond grading fluorescent lamps (6 500 K). The analysis focused on color changes, recovery times, and the characteristics of infrared (IR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, and photoluminescence (PL) spectroscopy before and after exposure. The findings revealed that: After exposure to short-wavelength ultraviolet radiation, the samples exhibited a decrease in brightness, turning overall grayish, with color restoration occurring within 7 to 30 minutes. The infrared (IR) spectra displayed extremely weak absorption peaks/bands at 1 332 and 950 cm^-1 attributed to N⁺_s, as well as peask/bands at 1 344 and 1 130 cm^-1 attributed to N^-_s, indicating an extremely low nitrogen content in the samples, classifying them as type IIa. Following short-wavelength UV exposure, the peak at 1 344 cm^-1 intensified, while the peak at 1 332 cm^-1 weakened. The UV-Vis spectra confirmed that the pink color of the samples was due to NV color centers. After short-wavelength UV exposure, the absorption intensity at 637 nm (NV^-) weakened. Changes in the absorption intensities of NV⁰ and NV^- color centers, along with shifts in the centers of their respective absorption edge bands, were identified as the primary reasons for the color alterations. The PL spectra exhibited prominent luminescent peaks at 575 and 637 nm, attributed to NV⁰ and NV^-, respectively. The intensity of the NV⁰ peak was 2.5 to 6.5 times that of the NV^- peak. In most samples, weak double peaks at 736.6 and 736.9 nm (SiV^-) were also observed. After exposure to short-wavelength ultraviolet radiation, the luminescent peak intensities of NV⁰, NV^-, and SiV^- decreased to varying degrees, with the most pronounced decrease observed for NV⁰ and its luminescent sideband. This indicates that short-wavelength UV exposure caused a redu ction in the concentration of NV⁰, NV^-, and SiV^- color centers to varying extents, with NV^- experiencing the most significant decrease, suggesting its greatest instability under 225 nm UV light. Based on a comprehensive analysis, the samples are classified as pink due to NV color centers. Upon exposure to 225 nm UV radiation, rea ctions such as N⁺+NV^-↔N⁰+NV⁰ and N⁺+SiV^-↔N⁰+SiV⁰ occur, as well as N⁰+NV⁰↔N^-+NV⁺ or X^+/0+NV⁰↔X^0/-+NV⁺, leading to the formation of NV⁺. Changes in the zero-phonon line intensity and the center of the absorption edge band of NV^0/- color centers result in significant color of the samples. Exposure to white light was found to restore the color of the samples to their original state.
		2025 Vol. 45 (11): 3190-3197 [Abstract] ( 11 ) PDF (17179 KB) ( 5 )

	3198	Weathering Mechanisms of Stone Sculptures at the Ming Imperial Mausoleum in Fengyang, China
		HUANG Huang¹, WANG Yu-long², SHI Yu-chen¹, ZHANG Bin-bin³, TANG Geng-sheng⁴
		DOI: 10.3964/j.issn.1000-0593(2025)11-3198-09
		In this study, a systematic analysis of the weathering damage of stone sculptures in the Ming Dynasty Emperor's Mausoleum in Fengyang, Anhui Province, was carried out, and the material properties and weathering mechanisms of the statues were revealed by X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), and super depth-of-field 3D microscopic techniques. XRD analysis shows that the stone is dominated by calcareous carbonate composed of quartz, dolomite, aragonite, and calcite, and the black pollutants on the surface mainly originate from MgO produced by the weathering of dolomite and the sulfide FeS. XRF detection showed the widespread presence of Ca, Si, Fe, S, Cl, etc., in which Cl^- and SO^2-₄ destroy the structure of the stone through soluble salt cycle crystallization, leading to scaling. Ultra-depth of field microscopy reveals that salt spray corrosion significantly reduces the density of quartz particles. Water absorption experiments confirm that the average water absorption rate of the stone is related to the difference in water content, which is influenced by the local environment. The results indicate that since the statues are not buried in the earth and are shallowly affected by groundwater, it is the air humidity and precipitation that accelerate the process of erosion by soluble salts. It is recommended that surface encapsulation materials be used to isolate moisture and contaminants. The results provide a scientific basis for the protection of stone carvings in the Ming Dynasty Emperor's Mausoleum, revealing the mechanism of multifactorial synergistic destruction of open-air stone cultural relics.
		2025 Vol. 45 (11): 3198-3206 [Abstract] ( 11 ) PDF (40879 KB) ( 2 )

	3207	Application of Non-Destructive Spectroscopic Techniques for Pigment Identification and Painting Skills Study of Large Format Oil Paintings
		ZHAO Dan-dan¹, YANG Qin^{1, 2}, WU Na^{1, 2}, LI Yu^{3, 4, 5}, ZHANG Tuo¹, YAN Yu¹, HAO Xin-ying⁶
		DOI: 10.3964/j.issn.1000-0593(2025)11-3207-09
		Many effective analytical techniques face limitations when applied in the field of cultural heritage conservation due to artifact size and on-site environmental constraints. Large-format oil paintings in museum collections present particular challenges, as they possess both movable and immovable characteristics, making efficient on-site analysis difficult. In this work, we selected the large-format oil painting “Autumn on the Dnieper River” from the collection of the National Museum of China as a case study. Considering the painting's specific attributes and the practical conditions of its conservation setting, a non-destructive multi-technique approach consisting of multispectral imaging (MSI), macro X-ray fluorescence (MA-XRF) mapping, and fiber optic reflectance spectroscopy (FORS), was employed for pigment identification and painting techniques investigation. The results demonstrate that: (1) clustering analysis based on macroscopic spectral imaging provides valuable information regarding artistic techniques and pigment classification; (2) segmentation of multispectral images based on the spatial distribution of surface pigments enables precise mapping of pigment application areas; and (3) in-depth analysis using FORS, combined with digital image extraction, establishes correlations between pigment distribution and material composition, thereby allowing accurate identification of pigment distribution on the painting's surface. The integrated application of these convenient and adaptable methods allows for the rapid and accurate acquisition of critical information about large-format oil paintings, including details of varnish and underdrawing layers, evidence of modifications and hidden information in the painting process, as well as the types and spatial distribution of pigments.
		2025 Vol. 45 (11): 3207-3215 [Abstract] ( 10 ) PDF (66073 KB) ( 1 )

	3216	A Study on the Morphology and Material Characteristics of Twisted Gold Threads From the Tang Dynasty Unearthed at the Tuyugou Grottoes in Xinjiang
		LIU Da-wei^{1, 2}, GU Yu-shan^2*
		DOI: 10.3964/j.issn.1000-0593(2025)11-3216-10
		This study focuses on four sets of twisted gold thread samples from Tang Dynasty lotus-patterned embroidered banners unearthed at the Tuyugou Grottoes site in Turpan, Xinjiang. A range of modern analytical techniques, including optical microscopy (OM), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), laser confocal Raman spectroscopy (Raman), and fiber microscopy identification, were employed to systematically investigate their structural morphology, metal and fiber composition, as well as the corrosion products and their formation mechanisms. The results show that the average width of the metal strips used in the twisted gold threads ranges from 480 to 498 μm, with a thickness of 30 to 50 μm. SEM-EDS elemental analysis reveals that the metal strips are primarily composed of copper-zinc alloys, with approximately 2 wt% zinc content. The corrosion products on the surface mainly include copper(Ⅰ) oxide (Cu₂O), atacamite [Cu₂(OH)₃Cl], and copper zinc chloride hydroxide [Cu₃Zn(OH)₆Cl₂]. Based on the distribution of the corrosion products, it is speculated that significant dezincification corrosion occurred in the buried environment, with localized Cl element enrichment on the surface, leading to the formation of chloride copper corrosion products. Furthermore, Raman spectroscopy confirmed the presence of the aforementioned corrosion phases: the red substance was mainly copper(Ⅰ) oxide, the green substance was a mixture of atacamite and copper zinc chloride hydroxide, and the black substance exhibited a clear carbon black signal, which is suspected to originate from soot deposited during religious offerings such as incense and candles. In terms of manufacturing techniques, the metal strip edges are smooth with no signs of pulling, and its uniform width and thickness suggest that the copper alloy was hammered into thin sheets and then cut into strips, which were spirally wound around cotton core fibers either by hand or using simple tools. Microscopic observation of the core fiber shows a natural twist in the longitudinal direction, a distinct central cavity, and a typical kidney-shaped cross-section, confirming that the core material is cotton fiber. Twisting tests revealed that the core fiber is a two-ply Z twist, and the metal strip is an S twist, consistent with the typical structural characteristics of traditional twisted gold thread. In conclusion, this study reveals the fundamental characteristics of the Tang Dynasty twisted gold threads from the Tuyugou Grottoes, including material selection, structural design, decorative techniques, and corrosion behavior. Although these metal decorative textiles do not use precious metals, the use of brass material with gold-like treatment, the two-ply cotton core, and the reasonable design of the manufacturing process balance visual effects and cost control, highlighting the unique and regional development of decorative techniques in religious textiles along the Silk Road.
		2025 Vol. 45 (11): 3216-3225 [Abstract] ( 6 ) PDF (106800 KB) ( 1 )

	3226	Data Quality Control and Rapid Retrieval Algorithm for Ground-Based CO₂ Concentration Inversion
		LI Shu^{1, 3}, YANG Le-yi^{1, 3}, CHU Xiao-xue^{2, 3*}, YE Song^{1, 3}, SHI Hai-liang⁴, GAN Yong-ying^{1, 3}, WANG Xin-qiang^{1, 3}, WANG Fang-yuan^{1, 3}
		DOI: 10.3964/j.issn.1000-0593(2025)11-3226-09
		Accurate monitoring of atmospheric CO₂ concentrations is crucial for climate change mitigation. Ground-based remote sensing provides high spatiotemporal resolution data, yet its accuracy is affected by multiple factors. This study utilizes the SCIATRAN radiative transfer model to simulate radiation transmission processes under various observational conditions, analyzing impacts of a priori profiles, spectral resolution, solar zenith angle (SZA), relative azimuth angle (RAA), temperature, aerosol optical depth (AOD), and boundary layer humidity on CO₂ retrieval. The following data quality control standards are established: (1) During observations, implement angle tolerance limits based on predicted daily CO₂ levels: SZA≤1.5° and RAA≤28° for high-concentration periods, with stricter thresholds of SZA≤1° and RAA≤27° for low-concentration periods. (2) Retrieval processes must incorporate real-time temperature and pressure profile data, such as the ERA5 reanalysis dataset (European Centre for Medium-Range Weather Forecasts) featuring dynamically updated parameters. (3) Urban-type aerosols are adopted, excluding data where AOD>0.3 or humidity>80%. A novel Global-Local Synergistic Optimization (GLSO) algorithm is proposed by integrating the strengths of the Genetic Algorithm (GA) and the Levenberg-Marquardt (L-M) method. Implementation of GLSO on EM27/SUN observation data demonstrates significant improvements: compared with the conventional L-M method, GLSO reduces iteration counts by 40%, decreases CO₂ total column deviation from 0.85% to 0.80%, and achieves a 0.13% discrepancy with TCCON XCO₂ data, outperforming the 0.27% deviation from L-M. Furthermore, the GLSO-derived CO₂ concentrations show less than 1% deviation from official GOSAT CO₂ products. This study establishes a robust framework for enhancing the precision and reliability of ground-based CO₂ monitoring through the optimization of observational protocols and advanced retrieval algorithms.
		2025 Vol. 45 (11): 3226-3234 [Abstract] ( 9 ) PDF (11153 KB) ( 2 )

	3235	SWIR Spectral Characteristics and Mineral Phase Transformations: Multi-Indicator Synergistic Response for Granite Weathering Classification
		ZHANG Shuo^{1, 2, 3}, LI Yu¹, JIANG Tong^1*, HUANG Jian-han¹, HUANG Yin-wei^{1, 4}, TIAN Jing-chun³, SHAN Mao-yu¹, LI Pei-yao¹
		DOI: 10.3964/j.issn.1000-0593(2025)11-3235-11
		The weathering degree of granite is a critical factor governing the engineering geological characteristics and disaster risks of rock masses. However, traditional assessment methods suffer from limitations in single-dimensional parameter characterization and invasive sampling that compromises rock integrity. This study integrates chemical weathering indices and mineralogical features derived from short-wave infrared (SWIR) spectroscopy to establish a multi-dimensional, non-destructive evaluation framework for granite weathering. Taking the typical granite weathering profile in Guangde City as the research object, combined with physical and mechanical tests, X-ray fluorescence spectroscopy(XRF),and SWIR spectroscopy analysis, the co-evolution mechanism of element migration, mineral phase transition, and mechanical degradation during weathering was systematically revealed. The study reveals significant correlations between the physical-mechanical properties and chemical weathering indices of granite with varying weathering degrees. The STI index exhibits a distinct relationship with porosity. At the same time, CIA, CIX, WIC, WIG, and Rb/Sr ratios demonstrate significant linear relationships with dry density, water absorption, compressive strength, and ultrasonic wave velocity. SWIR spectral characteristics can dynamically characterize the mineral transformation sequence. The completely weathered layer exhibits absorption features dominated by montmorillonite and kaolinite,while the highly weathered layer demonstrates absorption characteristics primarily composed of montmorillonite and illite. Moderately/slightly weathered layers display similar absorption features of montmorillonite and prehnite. However, the significantly reduced absorption peak depth in slightly weathered layers, resulting from lower contents of montmorillonite and prehnite, serves as a diagnostic characteristic for identifying moderately/slightly weathered layers.The spectral absorption characteristics of minerals, including peak morphology, depth, and ratio parameters, exhibit quantitative correlations with established chemical weathering indices. Spectral analysis of mineral phase transformation processes reveals that the absorption feature depths at 1 400 nm (d_{1 400}) and 2 200 nm (d_{2 200}) demonstrate positive correlations with clay mineral content. Furthermore, the characteristic ratios of d_{1 400}/d_{1 900} and d_{2 200}/d_{1 900} serve as effective indicators of clay mineral weathering intensity, with higher values corresponding to more advanced weathering stages. Compared to the Si-Ti and Rb/Sr ratios, the chemical weathering indices defined based on mobile oxides, along with absorption peak depths and their ratios, demonstrate superior performance in evaluating granite weathering intensity. The proposed quantitative classification framework, built on the synergistic response of mineral transformations and spectral signatures, provides theoretical and methodological support for rapid identification of granite weathering grades and disaster risk mitigation.
		2025 Vol. 45 (11): 3235-3245 [Abstract] ( 9 ) PDF (23106 KB) ( 4 )

	3246	Based on the Analysis of Infrared Spectroscopy and XPS, the Mechanism of the Influence of Metal Ions on Fluorite Flotation Was Studied
		LÜ Zhi-yan¹, LIU Rong-xiang^1*, CAO Zhao², LI Jie³
		DOI: 10.3964/j.issn.1000-0593(2025)11-3246-08
		As a national strategic mineral resource, the efficient recovery of fluorite (CaF₂) faces major challenges: on the one hand, it is closely associated with calcareous minerals such as calcite; on the other hand, the interference of metal ions (Ca²⁺, Ba²⁺, Fe³⁺) in the flotation system leads to low selective separation efficiency. In this study, solution chemical calculation, zeta potential analysis, infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) analysis techniques were used to systematically reveal the microscopic mechanism of metal ions regulating the adsorption of octyl hydroxamic acid (OHA) on fluorite surface. It shows that the dominant components of metal cations change the surface zeta potential by compressing the double electron layer on the surface of fluorite under a certain range of pH values, resulting in a decrease in the negative zeta potential of the mineral surface, and the surface potential regulation of fluorite increases the adsorption capacity of OHA. FTIR results showed that OHA tube energy groups appeared in many places in the fluorite spectrum after OHA treatment, indicating that OHA was chemically adsorbed on the surface of fluorite. The absorption peaks of —CH₃, —CH₂—, CO, C—N, C—C—C, C—O, and N—O appeared in the spectra of fluorite treated with metal ions and OHA, and the absorption peaks were enhanced. XPS depth analysis revealed that the content of OHA adsorbed by fluorite after metal ions was significantly higher than that of OHA adsorbed by fluorite without metal ions. After the treatment of fluorite with metal ions and OHA, the binding energy offset of Ca(2p) increases. Ba and Fe can replace the surface Ca lattice site, and the intensity of the N(1s) peak increases, and a new bonding mode of Me—O—N is formed. Combined with zeta potential, FTIR and XPS analysis, the adsorption efficiency sequence of metal ions on fluorite and OHA is: Fe³⁺>Ba²⁺>(Ca²⁺/Ba³⁺/Fe³⁺)≥(Ca²⁺/Ba²⁺)≥(Ca²⁺/Fe³⁺)>Ca²⁺. The ternary interaction model of “metal ion-interface-reagent” established in this study provides theoretical support for the efficient flotation of fluorite under complex water quality conditions. The synergistic mechanism of lattice substitution-chemical adsorption found in this study points out the direction for the design of new flotation reagents.
		2025 Vol. 45 (11): 3246-3253 [Abstract] ( 6 ) PDF (5670 KB) ( 1 )

	3254	Optical Path Design for Laser Confocal Inverted Microscope Raman Spectrometer
		HUANG Bao-kun^1, SONG Xin-ze², CHENG Jing³, LI Yu-meng¹, HUANG Tian-yun-zi¹, SHEN Tian-yang¹, KONG Xin-lan¹, TAO Sha^1, ZHANG Yun-hong^4*
		DOI: 10.3964/j.issn.1000-0593(2025)11-3254-08
		Micro-Raman spectrometers with a confocal design exhibit advantages such as high sensitivity, high spectral resolution, and high spatial resolution—owing to their highefficiencyin utilizing excitation light energy and in collecting and transmitting Raman scattering signals. Thus, they have become one of the primary analytical tools in laboratories. Inverted microscopes, by orienting their light exit ports upward, offer advantages including minimal restrictions on sample volume, rapid sample replacement, and upward beam propagation (which is suitable for detecting samples in containers like petri dishes). As a result, they hold promising applications in fields such as biomaterials and optical tweezers-based Raman spectroscopy.In this study, a laser confocal inverted micro-Raman spectrometer was developed by independently designing the optical path (comprising a laser optical system, an inverted microscope, a Raman signal optical system, and a spectrometer) and integrating these components with commercially procured lasers and charge-coupled devices (CCDs) via reserved interfaces. This developed spectrometer features a stable structure, low stray light levels, minimal installation requirements, and convenient maintenance. In accordance with the General Specification for Raman Spectrometers (GB_T 40219—2021), the sensitivity and spectral resolution of the laser confocal inverted micro-Raman spectrometer were tested. The results showed:When the spectrometer's entrance slit widths were 50 and 20 μm, the spectral resolution at the 1 710 cm^-1 peak of a neon lamp was 2.5 and 1.5 cm^-1, respectively—meeting the Class II index for “spectral resolution” specified in the General Specification; When a laser (wavelength: 532 nm, output power: 50 mW) was used as the excitation source with an exposure time of 300 s, the signal-to-noise ratios (SNRs) of the third-order Raman characteristic peak of monocrystalline silicon reached 11∶1 and 20∶1 when using open-electrode CCDs and backscattering CCDs, respectively. Additionally, the fourth-order peak was observable—meeting the Class I index for “signal-to-noise ratio” in the General Specification. Furthermore, the diameter of the laser-focused spot was calculated using the Rayleigh criterion. When a Leica objective lens (50× magnification, numerical aperture [NA]=0.75, focal length=0.5 mm) was employed, the spot size after the laser was focused through the objective lens was approximately 0.433 μm. Using the optical imaging magnification formula, the magnification of the Raman signal optical system was calculated to be 200, resulting in a spot diameter of ~86.6 μm at the slit. Given the spectrometer's magnification of 1, the spot diameter reaching the CCD remained ~86.6 μm. With the CCD having a pixel size of 16×16 μm, the spot diameter occupied approximately 5.4 pixels. When the slit width was 50 μm, the image of the slit (formed by the spectrometer) occupied ~3.1 pixels on the CCD. These calculation results were verified through actual spot size measurements. Finally, details of the instrument design were discussed, including the design philosophy and opto-mechanical design method for the laser beam expander, the application of long-pass filters and associated optical path design, the numerical aperture matching between the spectrometer and the pre-slit lens, the spectrometer's structure, the selection of collimating mirrors and focusing mirrors, and the choice of incident angle for grating diffraction.
		2025 Vol. 45 (11): 3254-3261 [Abstract] ( 7 ) PDF (19445 KB) ( 3 )

	3262	Multi-Exposure Cumulative Fusion Algorithm for an Echelle Spectrometer
		WU Rui-peng¹, SUN Ya-nan¹, WANG Lei², LIU Jia¹, NI Yun-ling¹, YIN Lu^1*
		DOI: 10.3964/j.issn.1000-0593(2025)11-3262-06
		The echelle spectrometer, known for its high spectral resolution, is highly sensitive to environmental disturbances, with even minor fluctuations capable of inducing spot drift. Ensuring reliable spectral analysis, therefore, requires precise localization of the spot centroid. However, the instrument's wide dynamic range and broad spectral coverage pose challenges for conventional single-exposure methods, which often fail to exploit the detector's capacity while avoiding signal saturation fully. To overcome these limitations, this study introduces a multi-exposure cumulative fusion method for spectral acquisition and processing. Spectra are automatically captured at varying exposure times, filtered to retain valid frames, and subsequently merged with threshold-based processing to achieve both denoising and accurate centroid identification. Experimental results confirm that the proposed approach effectively prevents overexposure, reduces noise interference, and enables accurate spot signal detection. Compared to traditional high dynamic range acquisition methods, the proposed approach offers the advantage of balancing weak signal detection and preventing strong signal saturation. This work provides a robust and automated solution for advancing spectral data acquisition and processing.
		2025 Vol. 45 (11): 3262-3267 [Abstract] ( 6 ) PDF (8687 KB) ( 2 )

	3268	High Spectral Resolution Image Restoration Method Based on Filtered Phase Reconstruction
		ZHENG Lian-hui¹, XIE Yun²
		DOI: 10.3964/j.issn.1000-0593(2025)11-3268-10
		A High spectral resolution spectrometer system has been widely applied in the fields of astronomical detection, remote sensing imaging, and target identification due to its high precision and resolution in spectral information acquisition. Through spectral image reconstruction, grating spectra can be decomposed into two-dimensional slit images and one-dimensional spectral data. However, in practical applications, factors such as wavefront aberrations and environmental noise significantly degrade imaging quality, limiting the system's performance in complex scenarios. In particular, during slit imaging, wavefront aberrations lead to a reduction in spatial resolution, which in turn affects the accuracy of subsequent spectral analysis and data interpretation. To address these issues, this paper proposes a high spectral image restoration method based on filtered phase reconstruction. The method first employs a Hartmann-Shack wavefront sensor to measure the wavefront aberration within the optical system, with a root mean square (RMS) measurement error of 0.002 μm when compared to interferometric results. Based on optical principles, the filtering effect of the slit on the wavefront aberration is analyzed under different slit widths, laying the foundation for subsequent phase reconstruction. Based on this analysis, a wavefront phase filtering model suitable for slit imaging conditions is established, enabling accurate estimation of the point spread function (PSF) and providing a physical and mathematical foundation for image restoration. In the image restoration stage, non-blind image restoration techniques are applied to reconstruct high-quality slit images using the estimated PSF. Both numerical simulations and experimental results demonstrate that the proposed method effectively restores image details even under challenging imaging conditions such as large wavefront aberrations and low signal-to-noise ratios, significantly improving the spatial resolution and spectral stability of the imaging system. Compared to conventional methods that rely on adaptive optics (AO) systems for real-time correction, the proposed approach does not require additional hardware, offering greater flexibility and improved engineering feasibility. Furthermore, the experimental results also demonstrate that the method performs robustly across a wide spectral range and even under white light illumination, thereby further expanding the applicability of high spectral imaging technology in fields such as astronomical observation and ground-based remote sensing. In conclusion, the proposed image restoration method offers an effective technical solution for enhancing the performance of high-spectral-resolution spectral imaging systems under complex optical conditions, demonstrating strong practical value and broad application prospects.
		2025 Vol. 45 (11): 3268-3277 [Abstract] ( 4 ) PDF (14219 KB) ( 1 )

	3278	Evolution and Prediction of Land Use Simulation Model Based on Serpentine Route Method and Multispectral Technology
		ZHENG Yu-tao^{1, 2}, YANG Kai-xin³, MAO Hai-ying^1*, YU Jing-xin⁴
		DOI: 10.3964/j.issn.1000-0593(2025)11-3278-10
		This study utilizes multi-spectral MS300 data from Changping District, Beijing, monitored at five-year intervals (2010, 2015, 2020). Simultaneously, the serpentine route aerial survey method using unmanned aerial vehicles (UAVs) was employed to supplement data collection in key areas. Data fusion techniques were applied to tightly integrate RGB and multi-spectral data tightly, thereby mitigating the impact of weather and other factors on land classification accuracy in certain regions. The study also introduced methodologies, including the land-use dynamic degree and transfer matrix. Using the FLUS model, a comprehensive simulation and prediction of the land use situation in Changping District for 2035 was conducted. The analysis identified land-use change patterns in Changping from 2010 to 2020, with accuracy verified using the Kappa coefficient. Furthermore, incorporating eight driving factors (such as topography, geomorphology, and transportation) identified through multicollinearity tests performed using Python, Markov chain prediction within the FLUS model was used to forecast the land use changes in Changping District for 2035. The specific results are as follows: (1) In the land-use changes in Changping District from 2010 to 2020, grassland exhibited significant transformation, with a dynamic change rate of 23.88%. This change primarily involved conversion from northern areas to central and eastern regions. Water bodies and woodland showed steady growth, mainly through mutual conversions with cropland. Built-up (construction) land and cultivated land experienced minor reductions, with dynamic change rates of -1.64% and -0.36% respectively, indicating relatively stable changes. Compared with observed land-use outcomes, this study aligns with the “Returning Farmland to Forest and Grassland Program” land-use policy implemented between 2010 and 2020, which emphasized “strictly controlling the conversion of cultivated land to woodland, garden land, and other types of agricultural land”. This alignment also supports the reliability of the ZY-3 (Resource Satellite-3) MS300 multispectral data and the FLUS model. (2) Based on research and analysis of land-use type conversions in the Changping District from 2010 to 2020, this study utilizes the FLUS model to conduct a natural progression prediction of land-use types for 2035. We also simulated three scenarios—green/low-carbon development, cropland protection, and ecological conservation. The results indicate that by 2035, the degradation of grassland in the region will be relatively significant, while changes in other land-use types, such as built-up land, cultivated land, and water bodies, will remain relatively stable. Specifically, the land-use change trend in Changping District under the green and low-carbon scenario from 2020 to 2035 aligns closely with the land-use change patterns observed from 2010 to 2020. This alignment also corresponds with the policy of development oriented towards reduction. These results suggest that over the next decade, the urbanization pace in Beijing's Changping District will be relatively slow, and further economic development will not drastically disrupt fundamental land-use patterns in the short term. However, the degradation of grassland serves as a constant reminder of the importance of environmental protection. The findings of this study can provide a basis for reasonably predicting land-use type conversions in various provinces and cities, laying a theoretical and practical foundation for future urban planning and development.
		2025 Vol. 45 (11): 3278-3287 [Abstract] ( 9 ) PDF (25366 KB) ( 1 )

	3288	Study on Rapid Detection and Strategy Optimization of Scale Inhibitor Based on Raman Scattering Technology
		CAO Jia-lei^{1, 2, 4}, CHENG Zhi-yang³, WANG Jie^{1, 2, 4}, JIA Hui^{1, 2, 4*}
		DOI: 10.3964/j.issn.1000-0593(2025)11-3288-06
		Scale inhibitors play a critical role in reverse osmosis systems, and their trace detection is of great significance for ensuring the efficient and stable operation of the system. However, traditional ultraviolet-visible spectrophotometry (UV-Vis) has limitations in terms of sensitivity and accuracy. This study employs Raman scattering (RS) and surface-enhanced Raman scattering (SERS) technologies to develop a rapid detection method for the scale inhibitor aminotrimethylene phosphonic acid (ATMP) in reverse osmosis (RO) systems, comparing the performance and practical applicability of different methods. The results show that RS and SERS significantly outperform UV-Vis in terms of sensitivity, accuracy, and resistance to interference, with rapid response times. RS achieves detection times of less than 4 minutes within a range of 0.5~1.0 mg·L^-1, making it suitable for rapid quantitative detection of ATMP in concentrated water; SERS technology exhibits a higher sensitivity range in 0.1~0.5 mg·L^-1, making it suitable for precise identification of trace amounts of ATMP in feedwater. In industrial background water samples, RS and SERS maintain low error rates even under typical ionic and organic interference, demonstrating potential practical application prospects. Based on the characteristics of the applicable concentration ranges for RS and SERS, this study optimized the detection strategies for ATMP in feedwater and concentrated water, providing a feasible technical approach for efficient monitoring of scale inhibitors in RO systems.
		2025 Vol. 45 (11): 3288-3293 [Abstract] ( 8 ) PDF (2953 KB) ( 1 )

	3294	Characteristics of Microcrystalline Structure Evolution and Inorganic Mineral Components of Coals With Different Metamorphic Degrees
		JIA Jin-zhang^{1, 2}, XING Ying-huan^{1, 2*}
		DOI: 10.3964/j.issn.1000-0593(2025)11-3294-07
		To investigate the microcrystalline structural evolution characteristics and relative inorganic mineral content of coal at different metamorphic stages, this study characterized four coal samples with varying degrees of metamorphism using X-ray diffraction (XRD) experiments. Phase analysis and microcrystalline structural parameter calculations were performed. Building upon previous research, the evolution patterns of microcrystalline structural parameters in whole coal ranks were examined, and the evolutionary mechanisms of coal microcrystalline structures were explored. Research indicates that the microcrystalline structure parameters of coal exhibit nonlinear step changes with the reflectance of vitrinite. The fundamental structural units of coal gradually transform from “vortex-layered” to flat graphitic structures, undergoing a transition from gradual to abrupt changes. R_{o, max} ranges from 0% to 0.6%, during which the microcrystalline structure parameters of coal remain nearly constant, and coal rank evolution proceeds relatively slowly. R_{o, max} ranges from 0.6% to 1.3%. A rapid evolution phase commences, characterized by the swift detachment of aliphatic and oxygen-containing functional groups, which form numerous active sites and increase the probability of aromatization. R_{o, max}ranges from 1.3% to 2.4%; the development of coal ductility and stacking height lags behind the interplanar spacing. R_{o, max} that ranges from 2.4% to 3.3%, longitudinal development and growth essentially cease, and the graphite-like microcrystals in coal transform from “tall and slender” to “flat”. When R_{o, max} exceeds 3.3%, graphite content gradually increases, and the coal exhibits an aggregate of disordered aromatic carbon coexisting with ordered graphite microcrystals.
		2025 Vol. 45 (11): 3294-3300 [Abstract] ( 10 ) PDF (6540 KB) ( 2 )

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